Recherche avancée

Sur d’autres sites (5972)

• Why the bitrate shown during processing differs so much from the final bitrate after processing using ffmpeg ?

  28 juillet 2016, par rpgmaker

  Using ffmpeg, why the bitrate shown during processing differs so much from the final bitrate after processing ?

  This command on a 1080p source :

  ffmpeg -i "$name" -i "$subname" -map 0 -map 1 -vf scale=-1:720 -c:v libx264 -preset veryslow -crf 21 -c:a aac -b:a 256k -c:s:0 srt -disposition:s:0 default -metadata:s:s:0 language=eng -metadata:s:v:0 title="$title" "$new"

  Shows this output :
  

  Which essentially averages 1300-1400 kBit/s. But when I calculate the bitrate of the resulting video using mkvinfo -t the bitrate shown sits at 970-1000 kBit/s and that’s not even close to averaging the 1300 kBit/s shown throughout processing. What is causing the disparity ?

• Process video with frame averaging to produce long exposure final frame

  4 mars 2020, par user3925023

  I’m looking for a FFMPEG script able to process a video file, create frame averaging and save latest long exposed frame.
  My goal is to process the video enhancing the trasparent TV logo on the screen :
  

  Is this viable via FFMPEG ? thx

• CMTimeGetSeconds doesn't get the right video duration

  26 février 2015, par JLCastillo

  some users don’t get the right duration of videos they capture with their own device. The funny thing is others do actually see it right, using the same device models and OS version. Anyway, we observed it in a iPhone 5c 7.1.2 and an iPhone 5s 8.1.3.

  This code works for most users, but not all :

  ALAssetRepresentation *representation = [mediaObject.asset defaultRepresentation];
  
  NSURL *url = [representation url];
  
  NSDictionary *options = @{ AVURLAssetPreferPreciseDurationAndTimingKey : @YES };
  
  AVAsset *avAsset = [AVURLAsset URLAssetWithURL:url options:options];
  
  videoDurationTime = CMTimeGetSeconds(avAsset.duration);

  I asked them to send the input videos, and this is the output from "ffmpeg -i"

  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'bug_duration1.MOV':
  
    Metadata:
  
      major_brand     : qt
  
      minor_version   : 0
  
      compatible_brands: qt
  
      creation_time   : 2015-02-23 08:30:01
  
      encoder         : 8.1.3
  
      encoder-eng     : 8.1.3
  
      date            : 2015-02-23T16:30:01+0800
  
      date-eng        : 2015-02-23T16:30:01+0800
  
      model           : iPhone 5s
  
      model-eng       : iPhone 5s
  
      make            : Apple
  
      make-eng        : Apple
  
    Duration: 00:00:03.67, start: 0.000000, bitrate: 16793 kb/s
  
      Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709), 1920x1080, 16719 kb/s, 29.99 fps, 29.97 tbr, 600 tbn, 1200 tbc (default)
  
      Metadata:
  
        creation_time   : 2015-02-23 08:30:01
  
        handler_name    : Core Media Data Handler
  
        encoder         : H.264
  
      Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 61 kb/s (default)
  
      Metadata:
  
        creation_time   : 2015-02-23 08:30:01
  
        handler_name    : Core Media Data Handler

  The video is detected with a duration of several minutes. Did anybody face this problem before ?

  Thanks in advance.